San Giovanni a Teduccio is a coastal suburb in the east of Naples, in southern Italy.
The area took its name after the discovery of a marble bust of John the Baptist in a facility that belonged in the 4th century to Theodosia, one of the daughters of Roman Emperor Valentinian I. The name "Teduccio" is a deformation of her name and in Latin the settlement was known as Sanctus Johannis ad Theodociam.
The area has a population of some 30,000 inhabitants.
The area was incorporated into the city of Naples under Fascist rule. The area has been heavily developed since the end of World War II and it suffers the same problems of unemployment and crime that afflict many of the suburbs in Naples.
Historically, the area was at the center of early industry in Naples and contains the facility that produced the first railway in Italy, Pietrarsa, now a railway museum.
Coordinates: 40°50′N 14°19′E / 40.833°N 14.317°E